family member; household member; occupant
Refers to people living in the same house, including family and sometimes servants. Slightly formal or written style; in casual speech 家族 is more common for family members.
All the household members gathered and had dinner.
Please proceed with the contract after obtaining consent from the household members.
I told my family about the travel plans.
I got my family's consent about the move.
同居人 specifically means someone sharing a residence (not necessarily a relative), whereas 家人 more broadly covers all members of one's household, family or not.
世帯 is an administrative/statistical term for a household as a single unit, while 家人 refers to the individual people who make up that household.
家人 (かじん, household member) and 家臣 (かしん, a feudal retainer/vassal) sound alike and both involve 家, but they refer to completely different relationships.
counter for people
jia ren (hexagram 37 of the I Ching: the family)
Compound of 家 (house) and 人 (person). The reading かじん is the on'yomi for both characters.